My freshly rebuilt engine seized during the HPA breaking procedure

Sorry for the clickbaity title but despite me not blaming the procedure, it'd true because the engine seized in the middle of the second 15 minutes of it.

At some point I thought the piston rings seized because I went too aggressive on the 5-10s acceleration and 20-30s deceleration recommended by the course. 😀

Pictures and videos: https://photos.app.goo.gl/F8QhEcB5jMsxWv2H8

Hi everyone,

After almost a year of preparation, I realized a dream of mine which is rebuilding an engine, but it spun a bearing within the first 30 minutes.

I know diagnosing issues from pictures or videos is tough, but any advice would be appreciated.

• I bought a Civic EK4 with a B16A2 engine that spun bearings within 5 minutes of pushing it.

• A mechanic replaced the bearings, but it happened again.

• We found that the 3rd piston’s journals were undersized compared to the others, likely causing the rebuild to fail.

• I then purchased a healthy crank, new oil pump, rings, and bearings.

• The engine was in poor condition due to the previous owners using tap water for coolant. I had the cylinder borders filled with aluminum and resurfaced.

• The sleeves were honed, and everything was within specs according to the manual.

• I measured the main bearings tolerances but just realized I forgot to measure them for rod bearings.

• I installed the engine myself, following the manual and torque specs, and used assembly lube on moving parts.

• We cranked the engine with injectors unplugged to prime the oil.

I was away when the mechanic first started the engine. He sent me a video of the first start where he immediately gave it 50% throttle. Hard to believe, huh?

When I returned, the engine was misfiring, and I heard bearing noises. I was sure the bearings were the issue, but I prayed I was wrong.

I drained the oil and found nothing worrying but made a mistake by not dropping the pan.

I fixed the misfire by replacing an injector and proceeded with the break-in: 30 minutes of acceleration and deceleration, half at 30% throttle, the other half at 75%.

Halfway through, vapor started coming from the engine bay. The car didn’t stall; I stopped it myself. I found the radiator cracked and fumes escaping from the top.

The car wouldn’t restart until 20 minutes later, still with fumes, and the bearing noises returned.

My second mistake was deciding to gently drive it home. The engine stalled abruptly after a few seconds. I should have towed it—I might have saved the crank.

The result: all bearings were damaged, with the rod bearings of piston 3 spinning. Interestingly, the previous crank was damaged in the same spot.

I accept that my first build failed, but I want to learn from this before attempting another.

Possible causes:

• The mechanic revved the engine hard immediately after starting.

• Poor quality mineral oil (locally packaged SAE 40 API CF); but how bad would the oil have to be to cause this?

• Faulty oil pump; but the oil pressure light turned off as soon as the engine started. The pump was new but unbranded.

• Clogged oil lines in the engine or crankshaft; but my machinist assures me they were thoroughly checked.

• Bad luck; but I don’t believe in bad luck.

For my next attempt:

• I’ve ordered quality mineral oil.

• I’ll install an oil pressure gauge for startup.

• My machinist will grind the journal where the bearing spun and polish the others.

• I’ll be cautious and drop the pan if I hear any noise.

Thanks for reading until here. What do you think happened?

I think there may be something fundamentally wrong with that engine block. Perhaps a proper line-boring is in order. Or just start with another (running) engine.

From the information you've provided I think possibly your rod bearing clearance may have been too tight resulting in the failure of all 4. This 'could' have been exaggerated by the 50% throttle i mediately after start but provided the oil system had been properly primed then it is unlikely (still a stupid idea however). The main bearings are all showing signs of significant debris related damage as a result most likely of debris from the big end bearings being pumped through the system. It can be a bit tough with failures like this to know exactly what the chain of events was but insufficient clearance is my first guess, followed by inadequate cleanliness possibly.

Meant to comment early, sorry.

It's hard to make a guess, especially as you're dependent on what parties with vested interests have said, but those pictures seem to have some very weird wear and damage patterns.

The mains look like they've had a bunch of trash from the oil galleries carried into them, from a block that wasn't properly cleaned. I have vague memories of something similar that was put down to a rough finish on the oil drillings in the journals, but may be mis-remembering. The uneven wear across them is also strange - were the journals "polished" on the crankshaft?

The big ends are also looking odd, I would have expected even wear/damage across the bearings, but they look like they're only damaged to the sides, making me think, again, that they were "polished", in both sets of journals I'd be suspecting that more material was removed from the middle than the edges, affecting the dynamic wedges that support the bearings.

I don't like casting aspersions, especially against people I don't know, but the machinist and, especially the "mechanic" seem to be very questionable. Depending on the 50% throttle, that may not be too bad, if it was actually bringing it up to 2-2500rpm, especially if he's more used to pushrod V8s and flat tappet camshafts - it's the events leading up to that that are important, the use of assembly lube, pre-oiling by cranking with the plugs out and a gauge to make sure there's pressure (I like to do so with the valve/cam' cover off to visually check), before starting it.

But if he winged it straight of the start, to much higher rpm, then that is definitely a different story - like if that video was the one he sent! In that there was clearly a problem right from the start, and by "start" I mean when that guy got his hand on his first tool!

You WON'T want to read this, but I'd strongly recommend you check the camshaft journals and the bearing housings and caps for damage - I'm sure you're also going to find bad damage has been done to them, as well, from debris being pumped directly to them.

Also, check the oil pump - I make it a practice to strip, clean and, if required, re-work them before cleaning and assembling with some light grease - put together dry there's direct metal contact until it draws oil into it - and that's with reputable pumps - if you'd used a (cheap) pattern one, who knows what crap might still have been left inside it. many people figure "the oil filter will catch it", but some are better than others, and weak bypass springs might even let colder oil through instead of filtering it. At the very least. immerse it in some oil and rotate it backwards and forwards a few times to flush out any debris, and lubricate the gears - it also helps build oil pressure faster in the engine.

Sorry I can't be much help, and I do realise you're going to be working with a limited budget, resources, and parts availability - but engines cost money, and there are no short-cuts.